The therapeutic efficiency of adoptively transferred A-NK cells is a multiparametric process. It demands highly developed mechanisms of effector cell localization at sites of tissue metastases followed by other, ill defined processes that lead to the destruction of tumor cells. Visualization and localization of message, protein, or structural changes leading to, or resulting from each step in this dynamic process in essential in understanding the basis for adoptive immunotherapy as a therapeutic modality. Studies of therapeutic strategies based on stimulation of endogenous NK cells required a similar approach for mechanistic evaluation. Within the projects described here, this identification includes studies of tumors and tumor-containing tissues, quantitative resolution of successful NK cell delivery to the tumor site in association with characterization of cellular interactions occurring intra- and extra-vascularly with an assessment of the site of A-NK cell activation. The Structural Biology Imaging Center, of the Pittsburgh Cancer Institute (PCI) in which this core service will be performed, is designed with these functions in mind. The Core is equipped to perform a continuum of optical methods including all types of microscopy essential to this Program Project. Within the scope of this Program light microscopic techniques include: histological, immuno-histological, laser confocal, and in situ hybridization technologies. We will also provide support in all aspects of electron microscopic technique as needed. Our considerable experience in computerized image processing and morphometry will allow quantitative analysis of observed phenomena to corroborate subtle qualitative changes, and this a major function of the Core in this Program. At the electron microscopic level immuno-electron microscopic evaluation of specimens as a natural extension of the light microscopic analyses will be employed when needed. This Core is currently used extensively by several of the Projects involved in this Program and we expect a substantial increase in the use of optical techniques within the formal setting of this Program.